National Water Model Assimilation Gage Basin Boundaries

This resource includes a single GeoPackage containing upstream basin boundaries for 8,175 USGS streamflow gages used for data assimilation by v3.0 of the National Water Model. The file contains vector geometry and a single attribute ("provider_id") that indicates the associated USGS site code. Basin geometry is important for estimating drainage area and deriving areal statistics, such as mean areal precipitation. The list of included USGS gages was drawn from the National Water Model RouteLink files located here: https://www.nco.ncep.noaa.gov/pmb/codes/nwprod

Note that these basin boundaries are unofficial and may deviate significantly from official USGS estimates of contributing drainage area. These basin boundaries were derived by accumulating NHDv2 Catchments using the HyRiver suite of Python tools. See the "Drainage Area Delineation" example for more details: https://docs.hyriver.io/examples/notebooks/nwis_catchments.html